Inspection device with rotatable lighting element housing

ABSTRACT

The invention relates to an inspection device for monitoring containers, particularly bottles, comprising at least one transport path for supplying and removing the containers, a lighting unit, and optical measuring unit, and a control unit, wherein the lighting unit is surrounded by a transparent hollow body mounted in a rotatable fashion about the central axis, and the hollow body may be driven by a motor, either directly or via appropriate operative connections. Ideally, the hollow body is a tube made of a material or mixture of materials that is transparent to rays in the optically visible wavelength range, in the infrared range, and/or in the ultraviolet range, wherein the material is at least partially transparent to said rays.

The invention relates to an inspection device for checking containers, in particular bottles, said inspection device including at least one conveying section for supplying or removing the containers, an illuminating unit, an optical measuring unit and a control unit, wherein the illuminating unit is surrounded by a transparent hollow body that is mounted so as to be rotatable about the central axis and the hollow body is driveable in a motor-driven manner directly or by means of suitable operative connections. In an ideal manner, the hollow body is a tube produced from a material or a material mixture that is transparent to rays of wavelengths in the optically-visible range, in the infrared range and/or in the ultraviolet range, wherein the material is at least partially transparent to said rays.

Devices for illuminating and inspecting container bottoms are known and adequately described in the prior art. EP 0 894 544 A discloses an inspection machine where the containers, in this case bottles, are conveyed in a suspended manner above an illuminating device. The illuminating device itself is a cuboid-shaped block that shines through the bottles from below. In principle, said devices are proven and suitable, but they have to be cleaned relatively frequently in order to ensure reliable operation and meaningful measured values.

DE 10 2005 057 872 A1 proposes producing the conveyor, which is illuminated from below and on which the bottles to be inspected stand, so as to be transparent and in the form of a turntable. This reduces the contamination on the illuminating unit itself but solid and liquid adhesions on the transparent turntable itself also require regular cleaning.

Consequently, it is the object of the invention to make available a device where the amount of time and money spent on cleaning is reduced.

This object is achieved by the inspection device for checking containers, in particular bottles. The inspection device includes at least one conveying section for supplying and removing the containers, an illuminating unit, an optical measuring unit and a control unit. The conveying section, in this case, can be one or more conveyor belts, conveying stars or a combination of conveyor belts and stars. The core of the inspection device, in this case, is the illuminating device, which is surrounded by a transparent hollow body that is mounted so as to be rotatable about the central axis, the hollow body being driveable in a motor-driven manner directly or by means of suitable operative connections. Dirt, label residue, dust and moisture can be removed from the monitoring region in this manner without interrupting the actual measuring or monitoring processes. The axis of rotation of the hollow body, in principle, can be aligned in an arbitrary manner. In an ideal manner, the axis of rotation of the hollow body is aligned parallel or transversely relative to the conveying direction of the containers.

In an ideal manner, the hollow body is a tube produced from a material or a material mixture that is at least partially transparent to rays of wavelengths in the optically-visible range, in the infrared range and/or in the ultraviolet range. In principle, known materials from suitable PTFE, acrylic glass or tempered glass can be used for this purpose.

An improvement of the inspection device consists in that a diffusion element is located between the hollow body and the top side of the illuminating unit, said diffusion element resulting in the illuminating means being homogenized. In this case, the term top side of the illuminating device refers to the side that points to the container to be inspected or to the bottle to be inspected and by means of which the light is emitted. The corresponding counterpart is referred to as the bottom side.

In principle, the diffusion element can have a planar, level form, however it has been shown that, in an advantageous manner, it is arcuate and located between hollow body and the top side of the illuminating unit, the materials and the production processes for these types of diffusion elements, in principle, being known.

A further improvement of the inspection device can be achieved when a polarisation filter is provided that, in an ideal manner, is located between the hollow body and the top side of the illuminating unit and in an advantageous manner also has an arcuate form. The use of polarisation filters or circular polarisation filters for inspection machines is known and is utilized, for example, in order to achieve reliable detecting of transparent solids, such as, for example, films, in the container.

Suitable polarisation filters are produced, for example, by a polyvinyl alcohol film that can be stabilized mechanically by means of a two-sided coating of cellulose acetobutyrate. Additional materials are known in principle and can be used depending on the application.

In the case of a variant of the device, a cleaning unit is located on the hollow body of the inspection device, said cleaning unit, in an ideal manner, being located below the illuminating unit. Said cleaning unit can also include a feeding device. The feeding device has outlets or nozzles for supplying the outside surface of the hollow body and is suitable for gaseous or liquid media.

In an improved variant, the cleaning unit includes at least one removing device, which includes mechanical scrapers in the form of brushes, sealing lips made of a resilient material or suction elements, so as to remove solid or liquid adhesions from the surface of the hollow body. Through the rotation of the hollow body, the adhesions are conveyed in a permanent or sequential manner from the top side, that is from the inspection field, to the bottom side. Any suitable, necessary wet and/or dry cleaning process can be effected at this location without having to consider the measuring and inspection device.

The rotating hollow body of the inspection device can be open at least at one side for reasons of heat development or for the supplying of power. In this way, deposits can pass onto the inside surface and be conducted into the inspection field. An improvement is consequently to be seen in that the cleaning unit extends onto or into the hollow body in such a manner that at least solid or liquid adhesions can be removed from the outside surface of the hollow body and in an ideal manner are also removable from the inside surface. In the case of a cylindrical hollow body, a cantilever arm, which includes the suitable scraper, can extend into the interior and there carry out the cleaning work.

In the case of an alternative embodiment, the hollow body is closed and connected to a gas line, by means of which in normal operation an inert gas, in particular compressed air, can be directed into the interior of the hollow body. By maintaining a permanent over-pressure in the interior of the hollow body, contamination of the inside surfaces can be reliably avoided.

In addition, the invention also includes a method for inspecting containers, in particular bottles, where an inspection device according to one of the preceding embodiments is used.

The essential method steps are:

-   -   a) permanent or occasional rotation of the hollow body     -   b) containers supplied     -   c) suspended transport in the region of the inspection unit     -   d) inspection of the containers     -   e) removal of the containers

One improvement of the inspection method can be seen in that the surface of the hollow body is cleaned permanently or at intervals or a gas, ideally filtered compressed air, is permanently directed into the hollow body. In the interior of the hollow body, the pressure maintained is preferably greater than the ambient pressure and in an ideal manner exceeds the ambient pressure by 0.2 to 0.5 bars. The gas or the compressed air, which can be referred to as flushing gas, has a dual function, namely to keep the interior free of contamination and to cool the interior. Consequently, it can be advantageous for a cooling device to be located in the line path of the gas supply line, by means of which cooling device the gas can be cooled, at least sometimes. In addition, it can be advantageous to dry the flushing gas prior to introducing it into the hollow body.

The inspection device and the inspection method are explained below by way of examples. FIG. 1 shows a sectional drawing of the illuminating device 1 of the inspection device. The hollow body is a transparent tube 2 made of an acrylic glass that is transparent to UV light and, in the example shown, has a diameter of 130 mm. The tube 2 is mounted so as to be rotatable about an axis 3 emerging from the drawing plane. Many known solutions are available to the expert for the bearing arrangement and the driving means, the double bearing arrangement at both ends of the tube 2 and the driving means at one end of the tube selected here are not shown. The cuboid-shaped illuminating unit 1 is located in the interior of the tube 2, said illuminating unit resting on two support arms 4. The rear suspension of the support arms 4 and of the motor-driven driving means of the transparent tube 2 are not shown in any detail as the expert is familiar with such devices. The illuminating unit 1 includes a planar, horizontal support 5, on which is disposed a diode field, which includes a plurality of diodes 6, which are connected electrically to a voltage source in a manner not shown. Two arcuate elements are located above the illuminating device 1. The bottom arc is the diffusion element 7. The largest distance between the diodes 6 and the diffusion element 7, the depth of the dishing, is 40 mm. The diffusion element 7 is spanned at a smaller distance by a polarisation element 8, which comprises a linear polarisation foil in the example represented. The meaning of the references, even if not always mentioned expressly below, is identical in all the Figures.

FIG. 2 shows a top view of the device. The bottle 9 is situated on a conveyor belt 10 that conveys the bottle 9 in the direction of the arrow towards the illuminating unit 1. In the stage of the method shown, the bottle 9 is already situated in the effective range of the vertical lifting belts 11 and 12 directly in front of or already partially above the gap 14, which is formed between the supplying conveyor belt 10 and the removing conveyor belt 15. The illuminating unit (not shown) and the tube 2 that surrounds said illuminating unit and rotates about the axis 3 is situated below said gap 14.

In the example shown, the endlessly circulating lifting belts are driven at different speeds such that the bottle 9, situated in the effective range of the lifting belts 11 and 12, rotates about its central axis.

FIG. 3 shows a side view of the same device or of the same method. The illuminating device 1 with the rotating, transparent tube 2 is located in the gap 14 between the conveyor belts 10 and 15. The illuminating device 1 is spanned by the polarisation element 7 and the diffusion element 8. Two cameras 16 are placed above the gap 14, said cameras receiving the signals and forwarding them to an evaluating and control unit 17. A cleaning unit 18 is located below the tube 2 in the region of the gap 14. Said cleaning unit includes a spray head 19, a pump 20, a storage container 21, a collecting tray 22, a motor-driven pivotable scraper 23 and a drying unit.

Actuated by the evaluating and control unit 17, the outside surface of the tube 2 is sprayed sequentially by the spray head 19 by means of the pump 20. Prior to this in time or at the same time, the scraper 23, driven by the motor 28, is moved to the surface of the tube 2. The scraper 23 has double wiping lips, comparable to a windscreen wiper, and is produced from a silicone material. On account of said arrangement, part of the adhesion flows or drops from the deepest tube portion into the collecting tray 22. The remaining adhesions and moisture are removed by the scraper 23 and also drop into the collecting tray 22. The cleaning fluid is directed by means of a pipe line into the storage container 21, where it is available to be used again.

A drying unit is located downstream of the scraper 23 in the direction of rotation, said drying unit including a hot air blower 24, which accomplishes the final drying of the cleaned outside surface of the tube. The compressor 25 connected to the hot air blower 24 and the associated heat unit 26 are also actuated by the evaluation and control unit 17.

The surface of the protective tube 2 can consequently be cleaned in an optimum manner. Continuously abradant elements or scrapers, which themselves result in contamination, are avoided. In the present example, the surface of the tube 2 is monitored by the camera 27 which is downstream of the scraper 23 and of the hot air blower 24 in the direction of rotation. This corresponds to monitoring the cleaning performance of the cleaning unit 18. Error messages or deviations from the required value are also forwarded to the evaluation and control unit 17 and are processed there. 

1-21. (canceled)
 22. An inspection device for checking containers, said inspection device comprising at least one conveying section or one conveying star for supplying and removing the containers, an illuminating unit, an optical measuring unit and a control unit, wherein the illuminating unit is surrounded by a transparent hollow body that is mounted so as to be rotatable about the central axis, wherein the hollow body is driveable in a motor-driven manner directly or by suitable operative connections, and wherein an axis of rotation of the hollow body is aligned parallel or transversely relative to a conveying direction of the containers.
 23. The inspection device according to claim 22, wherein the hollow body comprises a tube produced from a material or a material mixture, the material or material mixture being transparent to rays of wavelengths in the optically-visible range, in the infrared range and/or in the ultraviolet range, and wherein the material or material mixture is at least partially transparent to said rays.
 24. The inspection device according to claim 22, further comprising a diffusion element located between the hollow body and a top side of the illuminating unit.
 25. The inspection device according to claim 24, wherein the diffusion element is located in an arcuate manner between the hollow body and the top side of the illuminating unit.
 26. The inspection device according to claim 24, further comprising a polarisation filter is located between the hollow body and a top side of the illuminating unit.
 27. The inspection device according to claim 26, wherein the polarisation filter is arcuate and is located between the hollow body and a top side of the illuminating unit.
 28. The inspection device according to claim 26, wherein the polarisation filter is located between the hollow body and the diffusion element or the sequence of polarisation filter and diffusion element is inverted.
 29. The inspection device according to claim 22, further comprising at least one cleaning unit located on the hollow body.
 30. The inspection device according to claim 29, wherein the at least one cleaning unit includes at least one feeding device, which includes outlets or nozzles for illuminating an outside surface of the hollow body, wherein the feeding device is suitable for gaseous or liquid media.
 31. The inspection device according to claim 29, wherein the at least one cleaning unit includes at least one removing device, which includes mechanical scrapers in the form of brushes, sealing lips made of a resilient material, or suction elements, in order to remove solid or liquid adhesions from the surface of the hollow body.
 32. The inspection device according to claim 31, wherein the removing device comprises the at least one mechanical scraper that is driveable in a motor-driven manner.
 33. The inspection device according to claim 29, wherein the cleaning unit extends onto or into the hollow body in such a manner that at least solid or liquid adhesions can be removed from an outside surface of the hollow body.
 34. The inspection device claim 22, wherein the hollow body is at least partially closed.
 35. The inspection device according to claim 34, wherein at least one gas line leads into an interior of the hollow body.
 36. The inspection device according to claim 35, wherein at least one gas line or opening leads out of the interior of the hollow body.
 37. A method for inspecting containers, said method comprising using the inspection device recited claim
 22. 38. The inspection method according to claim 37, further comprising: a) rotating the hollow body; b) supplying containers; c) suspending transport in the region of the inspection unit; d) inspecting the containers; and e) removing the containers.
 39. The inspection method according to claim 37, further comprising, permanently or at intervals, cleaning a surface of the hollow body.
 40. The inspection method according to claim 37, further comprising directing a gas into an interior of the hollow body.
 41. The inspection method according to claim 40, further comprising maintaining the interior of the hollow body at a pressure greater than ambient pressure. 